Elongated edge bonded multi-metal strip of dissimilar alloys



Feb. 1, 1966 E. M. SMITH 3,233,211

ELONGATED EDGE BONDED MULTI-METAL STRIP OF DISSIMILAR ALLOYS FiledI NOV.19, 1962 F2 j.

l L w United States Patent Ohio Filed Nov. 19, 1962, Ser. No. 238,613 9Claims. (CL 339-258) This invention relates to metal strips ofdissimilar electrically conductive alloys having coplanar juxtaposedlateral edges bonded together, and more particularly to such strips ofelectrically conductive copper based alloys, one only of which containsberyllium.

An object of this invention is to provide a strip body of at least onepair of electrically conductive strips having their adjacent edgesdirectly bonded to each other by interpenetration of the metal of thestrip, and with the bonded joint free from any extraneous bondingmaterial, and the zone of interpenetration of the alloys of the twostrips at their juncture is confined substantially to the plane definedby the original juxtaposed edges of the strip.

A specific object is to provide such a strip wherein one strip is acopper based alloy containing beryllium, and the other strip is adissimilar copper based alloy, such as brass, Phosphor bronze, ornickel-silver, and is free from beryllium.

Still another object is to provide an alloy strip wherein the bondedjoint is cold rolled and extremely sound, thus preventing fracturing andis substantially free from camber.

A specific object is to provide an electrical connector having twoportions of different alloys respectively so that one portion hasphysical qualities rendering it particularly desirable for permanentconnection to a conductor and the other part has different physicalcharacteristics rendering it particularly desirable for resilientreadily attachable and detachable electrical connections.

These and other objects of the invention Will become apparent from thefollowing description of a preferred embodiment of the invention,wherein reference is made 'to the drawings in which:

FIG. 1 is a top plan View of a multi-metal strip of dissimilar alloysembodying the invention, and including a developed view of an electricalconnector blank to be made therefrom, as shown by dot and dash lines;

FIG. 2 is a cross-sectional view of the strip of FIG. 1

and is taken on the line 22 of FIG, 1;

FIG. 3 is a front elevation of the completed connector formed from theblank indicated by the dot and dash lines .in FIG. 1; and

the fusion of two different alloys, they tended to interrnix in a mannerresulting in unsound and uneven welds. Also the width of the zone ofinterpenetration of the alloys in the bond varied widely andunpredicably and was greater than that necessary for many commercialuses.

In the prior art, connectors having a tang portion for permanentconnection to a conductor and a barrel portion for detachably receivinga conductor prong were, well known and strips for fabricating suchconnectors were preferably formed from beryllium copper alloys becauseof the desirable characteristics of such alloys, such as fatigueendurance, resiliency, stability in dimension and shape, and wearresistance. The use of such beryllium copper alloy materials presented aproblem since the tang portions to which the lead conductors wereattached were not capable of being crimped for attachment of the leadconductors when the alloy had the desired characteristics at the barrelportion for resiliently retaining a prong connector. In order to renderthe connecting portion ductile and crimpable, the tang portion was heattreated. However, the heat treatment could not be confined to the tangportion alone, particularly where the connector was of a diminutive sizeuseful in miniaturized circuits. The heat treatment deleteriouslyaifected the properties of the barrel portion, thus reducing the overallefiiciency and quality of the finished product.

One alternative to the use of beryllium copper alloy to avoid the abovementioned difliculties was to make the entire conductor of some otherelectrically conductive material which was readily crimpablefor example,brass. Although the use of brass avoided the use of beryllium copperalloys, the fabricated connectors lacked many of the desired propertiesand therefore presented problems of frequent replacement, inaccuratefunction, and decreased conductivity.

In accordance with the present invention, as illustrated in the drawing,an elongated strip of beryllium copper alloy and an elongated strip ofcopper based alloy selected from the group consisting of brass, Phosphorbronze, and nickel-silver, have their adjacent lateral edgessubstantially at a right angle to the faces of the strips and juxtaposedagainst each other throughout their length and directly bonded togetherby the interpenetration of the metals to form a narrow bonding andinterpenetration zone confined substantially to the plane of theoriginal edges and with a joint substantially free from extraneousmetal.

The width of the bond in the fusion zone may be approximately 0.005inch, a width heretofore not obtainable. In fact, the width may rangefrom about 0.003 inch to about 0.030 inch.

Both of the strips are electrically conductive, one being ductile andreadily deformable for a permanent connection, and the other havinggreater fatigue endurance, stability in dimension and shape, and wearresistance, and resilience than the one strip, and being desirable for adetachable connection. The two strips are bonded to each other at theirlateral edges by arc welding in tungsten inert gas with accuratelycontrolled power input and concurrent accurate relative movement of thearc and strip endwise of the strips to produce a joint due tointerpenetration of the alloys of the strips and free from extraneousbonding material, the interpenetration zone .being confined laterally ofthe strips substantially to the plane of the original edges and thejoint being substantially free from camber. The bonded strips are thencold rolled endwise of the joint under pressure which reduces thethickness of the joined strips and the joint, thus pro- ,viding anelongated edge bonded, multi-metal strip of dissimilar alloys.

Metal strips according to this invention are particularly .useful forthe types of electrical connectors used in fminiaturized circuitsincluding connecting sockets, terminals, prongs, modules, and contacts,where one strip of the metal forms the barrel and the other strip formsthe tang.

The following are test results of a connector made from beryllium copperand brass in accordance with this Tensile specimens were also takenacross the joint before and after heat treatment. In both cases,fracture occurred in the brass area and not at the joint.

Referring to FIG. 1, there is shown an elongated multi metal edge-bondedcomposite strip 1 of dissimilar metal alloys. One portion 2 preferablyis from the class consisting of brass, Phosphor bronze, andnickel-silver, and substantially free from beryllium content. Theportion 2 is soft and ductile and possesses excellent crimpability. Theother portion 3 is of electrically conductive sheet metal alloy,preferably a copper base alloy containing beryllium. The two portions 2and 3 are separately formed and rolled alloy strips and their adjacentlateral edges are substantially at a right angle to the face of thestrips, as illustrated in the drawing, and are juxtaposed and directlybonded together throughout their length by interpenetration of thealloys of the two strips in a narrow zone of interpenetration, indicatedat 4, which is confined substantially to the common plane of thejuxtaposed edges and between the planes of the opposite faces of theoriginal strips forming the portions 2 and 3.

The bonding is accomplished by arc welding and the resultant joint isfree from any extraneous bonding material.

The resultant composite strip, including the joint, is cold rolled as aunit.

The arc welding is performed by tungsten arc welding equipment andtechniques while the electrode and instantaneous point of welding areprotected by inert gas. During welding the amperage supplied, thepositions of the electrode, strips, and joint, respectively, areprecisely controlled. A precision power unit so controls the electricalphenomena that the amperage does not vary from that selected more than0.10 percent.

The following are examples of preferred embodiments of the invention andare presented for purposes of illustrating and explaining the inventionand are not to be considered as limitations thereof.

Example 1 A coiled strip of brass 0.05 inch in thickness and 250 feetlong, and a strip of beryllium copper alloy 0.05 inch in thickness and250 feet in length, were maintained in intimate edgewise contact whiletheir juxtaposed edges were passing over a stationary tungsten inert gaswelding electrode at the rate of 5 to 6 feet per minute at 130 amps.controlled so that the amperage variance was less than 0.1 percent fromthe setting.

Example 2 A 20-foot length of 0.05 inch thickness bronze strip and a20-foot length of 0.05 inch thickness of beryllium copper alloy stripwere joined by the procedure of Example l, with the exception that thestrips were passed over the electrode at the rate of 4 feet per minuteat an amperage setting of 95.

Example 3 Metal strips of nickel-silver and beryllium copper alloyhaving a 0.05 inch thickness and feet in length, respectively, werejoined by the procedure of Example 1, with the exception that the stripswere passed over the electrode at the rate of 4 feet per minute at anamperage setting of 100.

Example 4 Strips of brass and beryllium copper alloy of 0.05 inchthickness and 250 feet in length, respectively, were joined by theprocedure of Example 1, with the exception that the strips were heldstationary and the welding electrode was passed over them at the pointof edgewise juncture at the rate of 4 and 3 feet per minute at anamperage setting of 95 and 80.

In all of the above examples, the bonded metal strips as a unit, andincluding the joint, were cold rolled to a thickness of 0.032 inch.

Test results of tensile specimens taken from the joined strips from eachof the above examples exhibited no fracture at the bonded joint.

Various beryllium copper alloys strip may be used for the portion 3 ofthe composite strip provided they have the desired physicalcharacteristics for the part to be made therefrom.

Referring next to FIG. 3, there is shown an electrical connector 5 madefrom the composite strip in accordance with this invention. The blankfor the connector is indicated at 5a in FIG. 1 and is cut from the stripl by stamping and formed. The resultant connector has a tang 6 which isfrom the portion 2 of the strip and consequently is sufficiently softand ductile for crimping around a conductor or like article but strongenough to hold its crimped position. The connector has a barrel 7 whichis from the portion 3 of the strip 1 and has suficient strength andresiliency to provide the maximum spring temper desired so that thebarrel can resiliently grip a prong inserted therein.

The composite strip may be used for forming other articles in which thedual characteristics are found desirable.

This advance over the prior art combines for the first time theproperties of two metals in a composite, uniform strip and solvesproblems in those products which require two different levels ofstrength, hardness, deformability and resiliency.

Having thus described my invention, I claim:

1. A metal strip body comprising at least one pair of metal alloystrips, one strip being electrically conductive and readily deformableand capable of remaining in its deformed condition, the other stripbeing resilient and electrically conductive and having high fatigueendurance, stability in dimension and shape, and high wear resistance,each greater than that of said one strip, and said pair of strips havingadjacent edges substantially at a right angle to the faces of the stripsand coplanar and against each other throughout their length and directlybonded to each other by interpenetration of the metal alloys of thestrips, with the bonded joint essentially free from any extraneousbonding material, said zone of interpenetration of the metal alloys ofthe two strips at their juncture being confined substantially to theplane defined by the original juxtaposed edges of the strip and beingfrom about 0.003 inch to 0.03 inch in width edgewise of the strips andbeing confined, flatwise of the strips, between the planes of the facesof the strips.

2. A body according to claim 1 wherein the overall width of theinterpenetration zone is less than 0.005 inch.

3. A body according to claim 1 wherein said other strip is a copper-baseberyllium containing alloy.

4. A body according to claim 1 wherein both of said strips of the pairare copper base alloys, and one of said strips contains beryllium andthe other is free from beryllium.

5. A body according to claim 1 wherein one of said strips isa copperbased alloy containing beryllium and the other of said strips is a metalalloy selected from the class consisting of brass, Phosphor bronze, andnickelsilver.

6. An electrical connector having one strip metal portion adapted forconnection to a lead conductor by cold permanent deformation of theportion and having a second strip metal portion having a resilientbarrel adapted to receive a connector therebetween and engage theconnector with yielding pressure, said portions having adjacentjuxtaposed strip edges substantially at a right angle to the faces ofthe strip portions and bonded to each other by the interpenetration ofthe metal of the portions with a bonded joint essentially free from anyextraneous bonding material, the zone of interpenetration of the metalsof said portions at the joint being confined substantially to a planedefined by the juxtaposed edges, and being from about 0.003 inch to 0.03inch in width in the plane of the strips and being confined flatwise ofthe strips between the 2,417,967 3/1947 Booe. planes of the surfaces ofthe strips. 2,448,268 8/1948 Larkin 339-262 7. An electrical connectoraccording to claim 6 Where- 2 453 552 1/1949 131m 29 430 X in saidportions are copper base alloys, said second portion 2,488 652 11/1949Adams q5 contains beryllium, and said one portion is substantially 5 a Mfree from beryllium. S16g- 8. An electrical connector according to claim6 wherein 2,801,402 7/ 1957 Barnes t the overall Width of theinterpenetration zone is about 2,834,870 5/1958 Platte 219-75 i 1 O n toac Ordfigt 6 h rein 3,066,275 11/1962 Hannnell 339-258 X .necicacnecrc nocirn we said one portion is a metal alloy selected from the class002136 4/1963 Peterson er a1 u 339 276 X consisting of brass, Phosphorbronze, and nickel-silver. FOREIGN PATENTS References Cited by theExaminer 1,108,263 3/ 1955 France.

UNITED STATES PATENTS JOSEPH D. SEERS,P" "E 1,996,775 4/1935 Sims 29-480

1. A METAL STRIP BODY COMPRISING AT LEAST ONE PAIR OF METAL ALLOYSTRIPS, ONE STRIP BEING ELECTRICALLY CONDUCTIVE AND READILY DEFORMABLYAND CAPABLE OF REMAINING IN ITS DEFORMED CONDITION, THE OTHER STRIPBEING RESILIENT AND ELECTRICALLY CONDUCTIVE AND HAVING HIGH FATIGUEENDURANCE, STABILITY IN DIMENSION AND SHAPE, AND HIGH WEAR RESISTANCE,EACH GREATER THAN THAT OF SAID ONE STRIP, AND SAID PAIR OF STRIPS HAVINGADJACENT EDGES SUBSTANTIALLY AT A RIGHT ANGLE TO THE FACES OF THE STRIPSOF COPLANAR AND AGAINST EACH OTHER THROUGHOUT THEIR LENGTH AND DIRECTLYBONDED TO EACH OTHER BY INTERPENETRATION OF THE METAL ALLOYS OF THESTRIPS, WITH THE BONDED JOINT ESSENTIALLY FREE FROM ANY EXTRANEOUSBONDING MATERIAL, SAID ZONE OF INTERPENETRATION OF THE METAL ALLOYS OFTHE TWO STRIPS AT THEIR JUNCTURE BEING CONFINED SUBSTANTIALLY TO THEPLANE DEFINED BY THE ORIGINAL JUXTAPOSED EDGES OF THE STRIP AND BEINGFROM ABOUT 0.003 INCH TO 0.03 INCH IN WIDTH EDGEWISE OF THE STRIPS ANDBEING CONFINED, FLATWISE OF THE STRIPS BETWEEN THE PLANES OF THE FACESOF THE STRIPS.